Medical devices include devices designed to be implanted into a patient. Some examples of these implantable medical devices (IMDs) include cardiac function management (CFM) devices such as implantable pacemakers, implantable cardioverter defibrillators (ICDs), cardiac resynchronization therapy devices (CRTs), and devices that include a combination of such capabilities. The devices can be used to treat patients or subjects using electrical or other therapy or to aid a physician or caregiver in patient diagnosis through internal monitoring of a patient's condition. The devices may include one or more electrodes in communication with one or more sense amplifiers to monitor electrical heart activity within a patient, and often include one or more sensors to monitor one or more other internal patient parameters. Other examples of IMDs include implantable diagnostic devices, implantable drug delivery systems, or implantable devices with neural stimulation capability.
Medical devices also include ambulatory or wearable medical devices (WMDs) such as wearable cardioverter defibrillators (WCDs). WCDs are monitors that include surface electrodes. The surface electrodes are arranged to provide one or both of monitoring surface electrocardiograms (ECGs) and delivering cardioverter and defibrillator shock therapy.
Some medical devices include one or more sensors to monitor different physiologic aspects of the patient. For example, the devices may derive measurements associated with a cardiac depolarization of the patient. Such measurements can provide useful information concerning the cardiac health of the patient.
Methods and systems to identify whether a patient is a responder for cardiac resynchronization therapy by using width of the QRS complex can be found in U.S. Patent Application Publication No. US 2008/0306568, filed Aug. 5, 2008.